Electronic communication devices such as telephones, smartphones, etc., which may be operated in a handsfree mode, typically make use of echo cancellation and/or echo suppression in order to compensate for an echo of an audio signal rendered by a loudspeaker of the electronic device, wherein the echo may have been captured by a microphone of the electronic device. The determination of the echo path for an electronic communication device is an important part of the signal processing for an effective conversation. When a talker hears an echo of his/her voice, such echo severely disrupts the talker's ability to converse naturally.
The efficient and correct operation of echo cancellation and/or echo suppression typically depends on a constrained and reasonable variation in the echo path over time, such as is expected with movement in the device or nearby objects. Hardware and/or software faults or failures in a system can lead to the possibility of sudden discontinuities or errors in the audio signals comprising the speaker output, echo reference and input microphone signal. Such discontinuities create unnatural variation in the echo path which can cause instability and failure of echo control systems. One aspect of this document addresses the technical problem of estimating the occurrence of such faults and discontinuity events.
In some systems or applications, there may be an unknown bulk delay that occurs due to the system hardware and/or software between an audio output and associated microphone input corrupted by echo. In modeling and echo path, it is not necessary to estimate the echo present in this bulk delay period. Another aspect of this document is to address an improved method for estimating this bulk delay resulting in improved echo control stability and lower computational complexity.